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    <title>Document</title>
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<script>
    // string number boolean null undefined object(array)  


    // 字符串  => 获取和设置一段文本内容

    // 如何创建字符串
    // 1. 字面量创建
    var str = "hello";
    console.log(str, typeof str);  // 'string'

    // 2. 构造函数创建
    var str = new String("hello");
    console.log(str, typeof str); // 'object'


    // var num1 = 1;
    // var num2 = new Number(1);
    // console.log(num1, num2);
    // console.log(num1 + num2);

    // var bool = true;
    // var bool = new Boolean(true);
    // console.log(bool, bool);







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